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arXiv 1908.053812019-08math.LO

A tractable case of the Turing automorphism problem: bi-uniformly $E_0$-invariant Cantor homeomorphisms

Bjørn Kjos-Hanssen

备注：: Accepted for publication in: Higher recursion theory and set theory. Lecture Notes Series, Institute of Mathematical Sciences, National University of Singapore, World Scientific Publishing, Hackensack, NJ

英文摘要：

A function $F:2^ω\to 2^ω$ is an $E_0$-isomorphism if for all $x,y\in 2^ω$, we have $xE_0y\iff f(x)E_0 f(y)$, where $xE_0y\iff(\exists a)(\forall n\ge b) x(n)=y(n)$. If such witnesses $a$ for $xE_0 y$ and for $f(x)E_0 f(y)$ depend on each other but not on $x$, $y$, then $F$ is called bi-uniform. It is shown that a homeomorphism of Cantor space which is a bi-uniform $E_0$-isomorphism can induce only the trivial automorphism of the Turing degrees.

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